Apastambagrihyasutra 1.1.20

1.1.20

apareṇāgniṃ pavitrāntarhite pātre 'pa ānīyodagagrābhyāṃ pavitrābhyāṃ trirutpūya samaṃ prāṇairhṛtvottareṇāgniṃ darbheṣu sādayitvā darbhaiḥ pracchādya \20\

To the west of the fire he pours water into a vessel over which he has laid (two grass blades called) purifiers, purifies (the water) three times with two northward-pointed purifiers, holds it on a level with his nose and mouth, places it to the north of the fire on Darbha grass, and covers it with Darbha grass.